Today, biomarkers play a key role in early diagnosis, risk stratification, and therapeutic management of various diseases. While progress in biomarker research has accelerated over the last 5 years, the clinical translation of disease biomarkers as endpoints in disease management and as the foundation for diagnostic products still poses a challenge.
MicroRNAs (miRNAs) are a new class of biomarkers. They represent a group of small noncoding RNAs that regulate gene expression at the posttranslational level by degrading or blocking translation of messenger RNA (mRNA) targets. MiRNAs are important players when it comes to regulate cellular functions and in several diseases, including cancer.
So far, miRNAs have been extensively studied in tissue material. It has been found that miRNAs are expressed in a highly tissue-specific manner. Disease-specific expression of miRNAs have been reported in many human cancers employing primarily tissue material as the miRNA source. In this context miRNAs expression profiles were found to be useful in identifying the tissue of origin for cancers of unknown primary origin.
Since recently it is known that miRNAs are not only present in tissues but also in other body fluid samples, including human blood. Nevertheless, the mechanism why miRNAs are found in body fluids, especially in blood, or their function in these body fluids is not understood yet.
Various miRNA biomarkers found in tissue material have been proposed to be correlated with certain diseases, e.g. cancer. However, there is still a need for novel miRNAs as biomarkers for the detection and/or prediction of these and other types of diseases. Especially desirable are non-invasive biomarkers, that allow for quick, easy and cost-effective diagnosis/prognosis which cause only minimal stress for the patient eliminating the need for surgical intervention
Particularly, the potential role of miRNAs as non-invasive biomarkers for the diagnosis and/or prognosis of kidney cancer has not been systematically evaluated yet. In addition, many of the miRNA biomarkers presently available for diagnosing and/or prognosing of diseases have shortcomings such as reduced sensitivity, not sufficient specificity or do not allow timely diagnosis or represent invasive biomarkers. Accordingly, there is still a need for novel and efficient miRNAs or sets of miRNAs as markers, effective methods and kits for the non-invasive diagnosis and/or prognosis of diseases such as kidney cancer.
The inventors of the present invention assessed for the first time the expression of miRNAs on a whole-genome level in subjects with kidney cancer as non-invasive biomarkers from body fluids, preferably in blood. They surprisingly found that miRNAs are significantly dysregulated in blood of kidney cancer subjects in comparison to healthy controls and thus, miRNAs are appropriated non-invasive biomarkers for diagnosing and/or prognosing of kidney cancer. This finding is surprising, since there is nearly no overlap of the miRNA biomarkers found in blood and the miRNA biomarkers found in tissue material representing the origin of the disease. The inventors of the present invention surprisingly found miRNA biomarkers in body fluids, especially in blood, that have not been found to be correlated to kidney cancer when tissues material was used for this kind of analysis. Therefore, the inventors of the invention identified for the first time miRNAs as non-invasive surrogate biomarkers for diagnosis and/or prognosis of kidney cancer. The inventors of the present invention identified single miRNAs which predict kidney cancer with high specificity, sensitivity and accuracy. The inventors of the present invention also pursued a multiple biomarker strategy, thus implementing sets of miRNA biomarkers for diagnosing and/or prognosing of kidney cancer leading to added specificity, sensitivity, accuracy and predictive power, thereby circumventing limitations of single biomarker. In detail, by using a machine learning algorithms, they identified unique sets of miRNAs (miRNA signatures) that allow for non-invasive diagnosis of kidney cancer with even higher power, indicating that sets of miRNAs (miRNA signatures) derived from a body fluid sample, such as blood from a subject (e.g. human) can be used as novel non-invasive biomarkers.